The present invention relates to a strap for hanging an instrument, more specifically, to a strap for an optical instrument such as a camera, a binocular and the like.
Conventionally, a camera or a binocular is hung from a neck when carried on. Generally, a strap is utilized to hang a camera or binocular, and both loose ends of the strap are respectively connected to a camera body or a binocular body. Further, the length of the strap is usually made adjustable to fit for each person who carries the camera or the binocular.
For example, in case of the binocular, a conventional type binocular has a pair of telescopic optical systems which are usually constructed to be foldable or swingable symmetrically about the center of the binocular so that the angle between the pair of the telescopic optical systems with respect to the axis of the swing movement can be adjusted corresponding to a distance between eyes of a user. Both loose ends of the strap are respectively anchored on upper surfaces of the telescopic optical systems by means of metal fittings, which are provided or integrally formed on the upper surfaces of the telescopic optical systems adjacent to eyepiece portions. Thus, the binocular is hung in a well-balanced condition with the eyepiece portion being faced upward when hung from a neck. There has been known a binocular in which the objective lenses are accommodated in a frame in such a manner that the optical axes of the objective lenses are arranged in parallel, the distance therebetween being kept constant, and the eyepiece portions are rotatable about the optical axis of the respective objective lens to adjust the distance between the eyepiece portions so as to correspond to a distance between eyes of an user of the binocular.
However, if the strap is attached to this binocular in the conventional manner, there arises a problem that the adjusted distance between the eyepiece portions may be undesirously changed while hung from the neck through the strap since the loose ends of the strap are connected directly to the foldable or swingable portion of the binocular, i.e., the eyepiece portion. And also it is not desirable in view of optics. For this reason, the strap used to be directly fixed on the immovable frame between the eyepiece portions.
In accordance with the above structure, however, the connecting portions of the strap are inevitably disposed close to the eyepiece portions, which causes the connecting portions to become obstacles when eyes are placed on the eyepiece portions.
That is, the end portion of the strap is usually folded back to overlap when fastened at the connecting portion so that the length of the strap can be adjusted, therefore the rigidity of the strap at the connecting portion is higher than the rest portion of the strap. For this rigidity of the strap, the connecting portion was inherently too hard to avoid interference with eyes when it is suddenly placed before eyes for observation shortly after the connecting portions of the strap have been kept standing in parallel with an optical axes of the eyepiece portions by being hung from a neck or a shoulder.